Pneumatic alleviator for hydraulic pumps



June 29 1926. 1,590,587

I F. M FARLAND PNEUMATIC ALLEVliATOR FOR HYDRAULIC PUMPS 2 Sheets-Sheet 1 Filed August 1 1924 I g H i June 29 1926. 1,590,587

F. M FARLAND PNEUMATIC ALLEVI'ATOR FOR HYDRAULIC PUMPS Filed August 1. 1924 2 Sheets-Sheet 2 I jig I p y m g Patented June 29, 1926.

FRANK MOFARLAND, or MExIco, MISSOURI.

PNEUMATIC ALLEVIATOR FOR HYDI IIAULIC'PUMPS.

Application and August 1, i924. Serial No. 729,555.

g It is the purpose of the present invention to provide a device of this kind for the purpose of alleviating, that is, for reducing the force with which a hydraulic pump discharges. In other words, the invention aims to render the discharge of the pump more uniform. In carrying out this purpose, the alleviator is designed for application in connection with the discharge side of the pump.

Another purpose is to provide an allevi-' ator for hydraulic pumps and wherein the plunger of the device is operated by hydraulic pressure on one side and compensated on the other side by air pressure and being cushioned on the hydraulic side by a dash-pot arrangement. When the plunger (which is hollow) is operated by hydraulic pressure thereunder, it rises, compressing the air in the chamber above the plunger to a pressure approaching the hydraulic pressure under the plunger. above the plunger is greater than the hydraulic pressure only-when the plunger is in its extreme lower'position. This is for the reason that the plunger at all times during the operation will be carried at a point high enough tov prevent engaging of the .dash-pot mechanism, the 'dash-pot connections being the extreme lower position of the plunger. When the fluid from the pump is discharging, the compressed air ex-- pands due to its elasticity, causing the plunger to descend and thereby create a uniform flow from the discharge side of the hydraulic pump.

Still another purpose is to provide a plunger of the buoyant type so that it will ascend as a result of the hydraulic pressure below. The plunger is buoyant due to its being hollow. A'further purpose is to provide a device of this kind wherein the plunger is packed as an ordinary plunger and is free to move in the cylinder upon any variation in pressure, the air being compressed or expanded as the case may be, thereby relieving any sudden change in pressure encountered which it isdesired to relieve.

' The chamber containing gland for the packing direct on the plunger,

The air pressure the air acts as a secondary packing being outside of this to permit a tight packed joint on the cylinder without the possibility of creating any undue friction on the plunger;

his to be understood that the particulars herein given are in no way limitative and that, while still keeping within thescope of the invention, any desired modifications of detail and desired proportions may be made in the apparatus according to the circumstances.

The invention comprises further features and combinations of parts to be hereinafter set forth, shown in the drawings and claimed.

In the drawings:

Figure 1 is a plan view of a conventional form of hydraulic. pump, showing the improved alleviatorasapplied to the discharge side of the pump. I

Figure 2 is an end 'view of the conventional pump as shown in Figure 1, showing the alleviator rising from the discharge pipe of the pump.

Figure 3 is a vertical sectional view through the alleviator.

Figure 4 is a horizontal sectional view 0 line 44 of Figure 3.

Referring to the drawings, 1 designates a conventional form of hydraulic pump, and 2 and 3 denote the discharge pipes which permit of the discharge of fluid from opposite sides of the pump piston. These pipes merge toward each other and are connected by means of a T 4 to which a single dis- 7 charge pipe 5 is connected. The pipe 5 carries the alleviator 6 which comprises a cylinder 7 of the general shape shown, al-

though it may be otherwise designed, and its lower end terminates in a base 8 which is bolted to the flanged end 9 of an extension 10 of the pipe 5.

The chamber 11 of the cylinder 7 at the lower endthereof has an opening 12 of less diameter than the diameter of the chamber 11, thereby causing a shoulder 13 to be formed. Openings 14 are formed through the shouldered portion so as to-permit of -a slow discharge of the liquid that may be entrapped between .the plunger 15 and the shoulder, thereby cushioning the plunger as for the reception of a plug 16*.

sand is removed, this opening, as previously stated, is tapped for the reception of the plug 16, thereby closing the, plunger and precluding fluid and above all insuring a buoyant plunger. This construction is to reduce the inertia of the plunger by means of taking advantage of the buoyant effect of the volume of the inside of the plunger which will permit of as free a reciprocation of the plunger as possible. The plunger at its lower end where the opening 16 is constructed is reduced, hence causing an extension 18 to be formed. This reduced extension enters the opening 12, that is, when the plunger has almost reached its extreme lower position. The other end of the plunger is rounded and closed, as shown.

The cylinder 7 adjacent its upper end is provided with annular countersinks 19 and 20, causing shoulders 21 and 22 to be formed. The countersink 19 receives packing 23 while the countersink 20 receives packing 24. The packing 23 constitutes means for precluding leakage of air around the plunger while the packing 24L precludes leakage around a cylinder 25 which telescopes the countersink 19 and the chamber 26 of which contains air compressed to such a pressure that the air in the chamber will be higher than the hydraulic pressure when the plunger is in the extreme lowered position. This is for the reason that the plunger at all times during operation will be carried at a point high enough to prevent engaging of the dash-pot connections. The dash-pot connections reside in.- the fact. of the reduced extension 18 entering the opening 12 at the base of the cylinder 7.

The cylinder 25 has an annular flange 27 which receives elongated cap screws or bolts 28 which thread into the enlarged end of the cylinder 7, thereby adjustably holding the cylinder 25 in position. The cylinder 25 acts as a packing ring to retain the packing 23 in the countersink, 19, holding it tightly but not tight enough to create undue friction upon the plunger, namely. "such as would retard the travel of the plunger in ascending and descending.

A packing ring 29 surroundsthe cylinder 25 and its extension flange enters the countersink 20, cooperating with the exterior surface of the .wall of the cylinder 25 for the chamber above the plunger; as a means of permitting compressed air to enter the chamber: and to provide means for attachment of a pressure gauge to permit ascertaining the pressure in the chamber.

The chamber 26 contains a suitable supply of lubricating oil 34, consequently on the air pressure'side of the plunger the oil is of sufficient quantity to insure against loss of air past the packing in the countersink 19 into the hydraulic sideof the alleviator or being lost from the device. This oil also acts as a lubricant for the plunger in the packing and the cylinder. The chamber 26 which contains compressed air acts as a gland for the packing direct on the plunger while the secondary packing being outside and around the outer circumference of the.cylinder. 25 permits a tight packed joint on the cylinder without the possibility of creating any undue friction on the plunger.

The plunger is free to move in the cylinder upon any variation in the pressure while the air'is compressed and,when allowed to expand, any sudden change in pressure encountered is relieved. Air pressure is t plied suitable for the pressure under which the mechanism is to operate.

When the pump is in action, it discharges through the pipe 5, causing the plunger to ascend and thereby compressing the air in the chamber 26.' In fact, when the plunger is rising, a hydraulic expansion takes place below the plunger, reducing the force with which the pump discharges from the pipe 5, and as the pump is. discharging the plunger descends and due to permitting of an expansion of the liquid, it is more uniform in its outflow.

It will be noted that as the plunger is nearing its extreme lower position. a certain ly passes out through the openings 14 which allows the plunger to gradually seat itself.

WVhile considerable stress has been exer-. cised with regard to using the present form of al-leviator on the discharge side of a hydraulic pump, it is'to be understood that the device involves other possibilities, for

with hydraulic containers, such as pipe lines,

beyond the/pump where sudden drafts, etc,

give pulsations; The device can also he used in some special cases where a high pressure is realized on the suction side of a pump.

The invention having been set forth, what is claimed is: I

1. An alleviator for hydraulic pumps comprising a cylinder including a chamber therein, a plunger mounted in said chamber,

a second cylinder entering the first cylinder and having a packing between the two, the second cylinder having a chamber for air pressure therein, and lubricant admission means attached to said second cylinder, the plunger acting to compress the air on the discharge stroke of the pump, whereby the plunger acts to maintain a uniform discharge of the liquid from the discharge side of the pump. I

2. An alleviator for'hydraulic pumps comprising a cylinder including a chamber therein, a plunger mounted in said chamber,

plunger acting to compress the air on the discharge stroke of the pump, whereby the plunger acts to maintain a uniform discharge of the liquid from the discharge side of the pump, said plunger having a dash-pot relation with the lower end of the first cylinder for cushioning the plunger when nearing its extreme lower position.

3. In a pump device as set forth, an alleviatorcomprlsing a cylinder having a hollow plunger therein directly exposed to the pressure ofthe pump fluid; a second cylinder operatively mounted in the first cylinder andhaving an air pressure chamber, the pressure of air in which causes a descent of the plunger upon the reduction of .fluid pressure below the plunger, and means in theair pressure chamber to pre elude the leakage of air between the second cylinder and the plunger.

4. In a pump device as set forth, an alleviator comprising a cylinder having a hollow plunger therein directly exposed to the pressu e of the pump fluid; a second cylinder operatively mounted in the first cylinder and having an'air pressure chamber, the ressureof air in which causes a descent of tlie plunger upon the reduction of fluid pressure below the plunger, and a dash-pot relation between the lunger and the lower end of the first. cylinder to cushion the plunger as it nears its extreme lower posi tion.

5. In a device as set forth, an alleviator comprising a cylinder having a "buoyant .plunger therein, a second cylinder operatively mounted in the first cylinder and having an air pressure chamber, the pressure of air in which causes a descent of the plunger upon the reduction of hydraulic pressure below the plunger, means in the air pressure chamber to preclude the leakage of air beofthe first'mentioned cylinder and in telescoping relation with the plunger, and bolts for securing the second said cylinder in place, the bolts being threadingly engaged with the first mentioned cylinder and the second cylinder having a flange through which said bolts pass.

7. In an appliance for the purpose indidated, a cylinder having a plunger mounted therein, the cylinder at one end being adapt ed for attachment to a fluid carrying conductor for communication with the same to subject the plunger to hydrostatic pressure within the conductor, the cylinder being counterbored at the remote end, a second cylinder seated in the counterbored portion of the first mentioned cylinder and in telescoping relation with the plunger, bolts for securing the second mentioned cylinder in place, the bolts being threadingly engaged with the first said cylinder and the second cylinder having a flange through which said bolts pass, and a packing ring in surrounding relation to the plunger and compressed between one end of the second mentioned cylinder and the bottom of the counterbored portion of the first cylinder.

8. In an appliance for the purpose indicated, a cylinder having a plunger mounted therein, the cylinder at one end being adapted for-attachment to a fluid carrying conductor for communication with the same to subject the plunger to hydrostatic pressure within the conductor, the cylinder being counterbored at the remote end, a second cylinder seated in the counterbored ortion of the first, mentioned cylinder and in telescoping relation with the plunger, bolts for securing the second mentioned cylinder in place, the bolts being threadingly engaged with the first mentioned cylinder and the second cylinder having a fla.nge through which said bolts pass, a packingring in surpressed between one end of the second mentioned cylinder and the bottom of the counterbored portion of the first cylinder, a packing ring in surrounding relation to the second mentioned Cylinder and entering the counterbored portion of the first said cylinder, packing 1n surrounding relation to the second mentioned cylinder and retained in FRANK MGFARLAND. 

